1. Field of the Invention
The present invention relates to a shaft seal structure for providing a sealing effect between relatively movable mechanical elements such as a reciprocating or rotating shaft and a casing or cylinder concentrically receiving said shaft so as to avoid the possibility of fluid leakage therebetween.
2. Description of the Prior Art
A prototype shaft seal structure will be explained by way of example with reference to FIGS. 1 and 2. In a shaft seal structure widely used, an annular seal groove 3 of rectangular configuration is formed on the outer periphery 21 of a carrier 2 and a pair of seal rings 4 of rectangular cross section are carried therein in side-by-side fashion, each of which is normally formed with a circumferential gap to permit the rings to be radially expandable to sealably engage their peripheries against the cylinder.
In the conventional shaft seal structure described above, however, the sealing operation is effected at two positions, namely between the outer peripheral surfaces 41 of both seal rings and the inner wall 51 of cylinder 5 and between a radial wall 31 of the annular seal groove 3 and one of the radial, side faces 42 of one of the seal rings 4. Thus, the resultant sealing performance of conventional shaft seal structures in not completely satisfactory and such being the case, it has been earnestly desired to develop a shaft seal structure capable of enjoying a more satisfactory sealing performance.